Every summer, blue crabs migrate north in the Chesapeake Bay to spawn. Once females have spawned, which they only do once in their lifetime, they migrate back down to the lower Bay area to lay their eggs. Our lab is using a combination of mark-recapture and shell-chemistry analysis to learn more about which nurseries these female crabs are coming from. The best way to help sustain a healthy abundance of blue crabs is to protect the spawning females. What we learn from this study may help managers target their efforts.